patch 8.1.1032: warnings from clang static analyzer

Problem:    Warnings from clang static analyzer. (Yegappan Lakshmanan)
Solution:   Fix relevant warnings.
diff --git a/src/regexp.c b/src/regexp.c
index 5557987..0a6695c 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -2785,7 +2785,7 @@
     *place++ = op;
     *place++ = NUL;
     *place++ = NUL;
-    place = re_put_long(place, (long_u)val);
+    re_put_long(place, (long_u)val);
 }
 
 /*